The present invention is generally directed to structures for supporting concrete reinforcing members. More particularly, the invention is directed to a chair for supporting two reinforcing bars in an orthogonal relationship as concrete is poured to form a concrete slab.
Steel reinforcement bars are typically used in concrete slabs and other concrete structures to provide structural support to the concrete. In slab applications, the bars are usually arranged in a rectangular lattice which is supported some distance above the ground or other surface on which the slab is to be poured. In this manner, the concrete may flow under and around the lattice, thereby encapsulating the lattice when the concrete hardens.
Prior structures for supporting the lattice above the ground, also referred to as chairs, have been lacking in several respects. Prior chairs have not provided stable support and have not effectively captured the reinforcing members to adequately keep them in the proper position as the concrete is poured. Also, some prior chairs have been difficult to use in that multiple pieces are required to capture the reinforcement bars. Further, many prior chair designs have been difficult to fabricate, which increases their cost.
What is needed, therefore, is an easy-to-use, low-cost structure for providing stable support for reinforcement bars in concrete slabs.
The foregoing and other needs are met by an apparatus for supporting reinforcement bars in a concrete structure. The apparatus includes a base member having a lower surface and an opposing upper surface, a pair of opposing first leg members extending upward from the upper surface of the base member, and a pair of opposing second leg members extending upward from the upper surface of the base member, where the second leg members are alternatingly disposed between the first leg members. An upper cradle is attached to the first leg members for receiving an upper reinforcement bar, and a lower cradle is attached to the second leg members for receiving a lower reinforcement bar.
The upper cradle comprises a first upper bar-support member and a second upper bar-support member. The first upper bar-support member has a pair of opposing first upper sidewalls separated by an upper channel, and the second upper bar-support member has a pair of opposing second upper sidewalls also separated by the upper channel.
The lower cradle comprises a first lower bar-support member and a second lower bar-support member. The first lower bar-support member has a pair of opposing first lower sidewalls separated by a lower-channel. One of the first lower sidewalls is attached to an adjacent one of the first upper sidewalls at an angle of about 90 degrees. Another of the first lower sidewalls is attached to an adjacent one of the second upper sidewalls at an angle of about 90 degrees. The second lower bar-support member has a pair of opposing second lower sidewalls separated by the lower channel. One of the second lower sidewalls is attached to an adjacent one of the first upper sidewalls at an angle of about 90 degrees. Another of the second lower sidewalls is attached to an adjacent one of the second upper sidewalls at an angle of about 90 degrees.
In a preferred embodiment, the apparatus includes upper retaining members protruding inwardly from the opposing first upper sidewalls and the opposing second upper sidewalls to retain the upper reinforcement bar within the upper cradle. These preferred embodiments also include lower retaining members protruding inwardly from the opposing first lower sidewalls and the opposing second lower sidewalls to retain the lower reinforcement bar within the lower cradle.
Preferably, the base member, first and second leg members, upper cradle, and lower cradle comprise a unitary structural element, such as a continuous piece of thermoplastic material formed by injection molding.